using System;
using System.Text;

namespace Encryption.AES
{
    class SubBytes
    {
        private static int[,] S_box =
		{
			  {0x63,0x7c,0x77,0x7b,0xf2,0x6b,0x6f,0xc5,0x30,0x01,0x67,0x2b,0xfe,0xd7,0xab,0x76},
			  {0xca,0x82,0xc9,0x7d,0xfa,0x59,0x47,0xf0,0xad,0xd4,0xa2,0xaf,0x9c,0xa4,0x72,0xc0},
			  {0xb7,0xfd,0x93,0x26,0x36,0x3f,0xf7,0xcc,0x34,0xa5,0xe5,0xf1,0x71,0xd8,0x31,0x15},
			  {0x04,0xc7,0x23,0xc3,0x18,0x96,0x05,0x9a,0x07,0x12,0x80,0xe2,0xeb,0x27,0xb2,0x75},
			  {0x09,0x83,0x2c,0x1a,0x1b,0x6e,0x5a,0xa0,0x52,0x3b,0xd6,0xb3,0x29,0xe3,0x2f,0x84},
			  {0x53,0xd1,0x00,0xed,0x20,0xfc,0xb1,0x5b,0x6a,0xcb,0xbe,0x39,0x4a,0x4c,0x58,0xcf},
			  {0xd0,0xef,0xaa,0xfb,0x43,0x4d,0x33,0x85,0x45,0xf9,0x02,0x7f,0x50,0x3c,0x9f,0xa8},
			  {0x51,0xa3,0x40,0x8f,0x92,0x9d,0x38,0xf5,0xbc,0xb6,0xda,0x21,0x10,0xff,0xf3,0xd2},
			  {0xcd,0x0c,0x13,0xec,0x5f,0x97,0x44,0x17,0xc4,0xa7,0x7e,0x3d,0x64,0x5d,0x19,0x73},
			  {0x60,0x81,0x4f,0xdc,0x22,0x2a,0x90,0x88,0x46,0xee,0xb8,0x14,0xde,0x5e,0x0b,0xdb},
			  {0xe0,0x32,0x3a,0x0a,0x49,0x06,0x24,0x5c,0xc2,0xd3,0xac,0x62,0x91,0x95,0xe4,0x79},
			  {0xe7,0xc8,0x37,0x6d,0x8d,0xd5,0x4e,0xa9,0x6c,0x56,0xf4,0xea,0x65,0x7a,0xae,0x08},
			  {0xba,0x78,0x25,0x2e,0x1c,0xa6,0xb4,0xc6,0xe8,0xdd,0x74,0x1f,0x4b,0xbd,0x8b,0x8a},
			  {0x70,0x3e,0xb5,0x66,0x48,0x03,0xf6,0x0e,0x61,0x35,0x57,0xb9,0x86,0xc1,0x1d,0x9e},
			  {0xe1,0xf8,0x98,0x11,0x69,0xd9,0x8e,0x94,0x9b,0x1e,0x87,0xe9,0xce,0x55,0x28,0xdf},
			  {0x8c,0xa1,0x89,0x0d,0xbf,0xe6,0x42,0x68,0x41,0x99,0x2d,0x0f,0xb0,0x54,0xbb,0x16}
		};
        private static int[,] InvS_box =
		 {
			 {82,9,106,213,48,54,165,56,191,64,163,158,129,243,215,251},
			 {124,227,57,130,155,47,255,135,52,142,67,68,196,222,233,203},
			 {84,123,148,50,166,194,35,61,238,76,149,11,66,250,195,78},
			 {8,46,161,102,40,217,36,178,118,91,162,73,109,139,209,37},
			 {114,248,246,100,134,104,152,22,212,164,92,204,93,101,182,146},
			 {108,112,72,80,253,237,185,218,94,21,70,87,167,141,157,132},
			 {144,216,171,0,140,188,211,10,247,228,88,5,184,179,69,6},
			 {208,44,30,143,202,63,15,2,193,175,189,3,1,19,138,107},
			 {58,145,17,65,79,103,220,234,151,242,207,206,240,180,230,115},
			 {150,172,116,34,231,173,53,133,226,249,55,232,28,117,223,110},
			 {71,241,26,113,29,41,197,137,111,183,98,14,170,24,190,27},
			 {252,86,62,75,198,210,121,32,154,219,192,254,120,205,90,244},
			 {31,221,168,51,136,7,199,49,177,18,16,89,39,128,236,95},
			 {96,81,127,169,25,181,74,13,45,229,122,159,147,201,156,239},
			 {160,224,59,77,174,42,245,176,200,235,187,60,131,83,153,97},
			 {23,43,4,126,186,119,214,38,225,105,20,99,85,33,12,125}
		};

        public static int GetSubByte(int key)
        {
            StringBuilder str = GetStr(key);
            byte[] buf = new byte[2];
            buf[0] = Convert.ToByte(str.ToString(0, 4), 2);
            buf[1] = Convert.ToByte(str.ToString(4, 4), 2);
            key = S_box[buf[0], buf[1]];
            return key;
        }
        public static int GetByteSub(int key)
        {
            StringBuilder str = GetStr(key);
            byte[] buf = new byte[2];
            buf[0] = Convert.ToByte(str.ToString(0, 4), 2);
            buf[1] = Convert.ToByte(str.ToString(4, 4), 2);
            key = InvS_box[buf[0], buf[1]];
            return key;
        }
        public static StringBuilder GetStr(int num)
        {
            StringBuilder s = new StringBuilder(8); 
            for (int i = 7; i >= 0; i--)
            {
                s =s.Append(num >> i & 1);
            }
            return s;
        }
    }
}
